Answer
$x = 18$
Work Step by Step
In a rhombus, diagonals bisect opposite angles. In this diagram, we have an angle bisected by the diagonal, so we can set the two expressions for the two angles equal to one another.
$5x - 30 = 3x + 6$
Add $30$ to each side of the equation to move constants to the right side of the equation:
$5x = 3x + 36$
Subtract $3x$ from each side of the equation to move variables to the left side of the equation:
$2x = 36$
Divide each side by $2$ to solve for $x$:
$x = 18$
